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authorSekhar Nori <nsekhar@ti.com>2009-11-03 15:14:13 +0530
committerKevin Hilman <khilman@deeprootsystems.com>2009-11-25 10:21:37 -0800
commita6c0f6eca1173e9d44f1f0fb9ecc832abd7d77d6 (patch)
tree57057404d156f4beff39c3e6d6fa7c6a62a9eaa6 /arch/arm/mach-davinci/cpuidle.c
parent1ef203c3242c17da6559c4be1aa91c689d3efbb0 (diff)
davinci: add CPU idle driver
The patch adds support for DaVinci cpu idle driver. Two idle states are defined: 1. Wait for interrupt 2. Wait for interrupt and DDR self-refresh (or power down) Some DaVinci SoCs support putting DDR in self-refresh (eg Dm644x, DM6467) while others support putting DDR in self-refresh and power down (eg DM35x, DA8xx). Putting DDR (or mDDR) in power down saves more power than self-refresh. The patch has been tested on DA850/OMAP-L138 EVM. Signed-off-by: Sekhar Nori <nsekhar@ti.com> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Diffstat (limited to 'arch/arm/mach-davinci/cpuidle.c')
-rw-r--r--arch/arm/mach-davinci/cpuidle.c197
1 files changed, 197 insertions, 0 deletions
diff --git a/arch/arm/mach-davinci/cpuidle.c b/arch/arm/mach-davinci/cpuidle.c
new file mode 100644
index 000000000000..97a90f36fc92
--- /dev/null
+++ b/arch/arm/mach-davinci/cpuidle.c
@@ -0,0 +1,197 @@
+/*
+ * CPU idle for DaVinci SoCs
+ *
+ * Copyright (C) 2009 Texas Instruments Incorporated. http://www.ti.com/
+ *
+ * Derived from Marvell Kirkwood CPU idle code
+ * (arch/arm/mach-kirkwood/cpuidle.c)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/cpuidle.h>
+#include <linux/io.h>
+#include <asm/proc-fns.h>
+
+#include <mach/cpuidle.h>
+
+#define DAVINCI_CPUIDLE_MAX_STATES 2
+
+struct davinci_ops {
+ void (*enter) (u32 flags);
+ void (*exit) (u32 flags);
+ u32 flags;
+};
+
+/* fields in davinci_ops.flags */
+#define DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN BIT(0)
+
+static struct cpuidle_driver davinci_idle_driver = {
+ .name = "cpuidle-davinci",
+ .owner = THIS_MODULE,
+};
+
+static DEFINE_PER_CPU(struct cpuidle_device, davinci_cpuidle_device);
+static void __iomem *ddr2_reg_base;
+
+#define DDR2_SDRCR_OFFSET 0xc
+#define DDR2_SRPD_BIT BIT(23)
+#define DDR2_LPMODEN_BIT BIT(31)
+
+static void davinci_save_ddr_power(int enter, bool pdown)
+{
+ u32 val;
+
+ val = __raw_readl(ddr2_reg_base + DDR2_SDRCR_OFFSET);
+
+ if (enter) {
+ if (pdown)
+ val |= DDR2_SRPD_BIT;
+ else
+ val &= ~DDR2_SRPD_BIT;
+ val |= DDR2_LPMODEN_BIT;
+ } else {
+ val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
+ }
+
+ __raw_writel(val, ddr2_reg_base + DDR2_SDRCR_OFFSET);
+}
+
+static void davinci_c2state_enter(u32 flags)
+{
+ davinci_save_ddr_power(1, !!(flags & DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN));
+}
+
+static void davinci_c2state_exit(u32 flags)
+{
+ davinci_save_ddr_power(0, !!(flags & DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN));
+}
+
+static struct davinci_ops davinci_states[DAVINCI_CPUIDLE_MAX_STATES] = {
+ [1] = {
+ .enter = davinci_c2state_enter,
+ .exit = davinci_c2state_exit,
+ },
+};
+
+/* Actual code that puts the SoC in different idle states */
+static int davinci_enter_idle(struct cpuidle_device *dev,
+ struct cpuidle_state *state)
+{
+ struct davinci_ops *ops = cpuidle_get_statedata(state);
+ struct timeval before, after;
+ int idle_time;
+
+ local_irq_disable();
+ do_gettimeofday(&before);
+
+ if (ops && ops->enter)
+ ops->enter(ops->flags);
+ /* Wait for interrupt state */
+ cpu_do_idle();
+ if (ops && ops->exit)
+ ops->exit(ops->flags);
+
+ do_gettimeofday(&after);
+ local_irq_enable();
+ idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
+ (after.tv_usec - before.tv_usec);
+ return idle_time;
+}
+
+static int __init davinci_cpuidle_probe(struct platform_device *pdev)
+{
+ int ret;
+ struct cpuidle_device *device;
+ struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;
+ struct resource *ddr2_regs;
+ resource_size_t len;
+
+ device = &per_cpu(davinci_cpuidle_device, smp_processor_id());
+
+ if (!pdata) {
+ dev_err(&pdev->dev, "cannot get platform data\n");
+ return -ENOENT;
+ }
+
+ ddr2_regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!ddr2_regs) {
+ dev_err(&pdev->dev, "cannot get DDR2 controller register base");
+ return -ENODEV;
+ }
+
+ len = resource_size(ddr2_regs);
+
+ ddr2_regs = request_mem_region(ddr2_regs->start, len, ddr2_regs->name);
+ if (!ddr2_regs)
+ return -EBUSY;
+
+ ddr2_reg_base = ioremap(ddr2_regs->start, len);
+ if (!ddr2_reg_base) {
+ ret = -ENOMEM;
+ goto ioremap_fail;
+ }
+
+ ret = cpuidle_register_driver(&davinci_idle_driver);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to register driver\n");
+ goto driver_register_fail;
+ }
+
+ /* Wait for interrupt state */
+ device->states[0].enter = davinci_enter_idle;
+ device->states[0].exit_latency = 1;
+ device->states[0].target_residency = 10000;
+ device->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
+ strcpy(device->states[0].name, "WFI");
+ strcpy(device->states[0].desc, "Wait for interrupt");
+
+ /* Wait for interrupt and DDR self refresh state */
+ device->states[1].enter = davinci_enter_idle;
+ device->states[1].exit_latency = 10;
+ device->states[1].target_residency = 10000;
+ device->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
+ strcpy(device->states[1].name, "DDR SR");
+ strcpy(device->states[1].desc, "WFI and DDR Self Refresh");
+ if (pdata->ddr2_pdown)
+ davinci_states[1].flags |= DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN;
+ cpuidle_set_statedata(&device->states[1], &davinci_states[1]);
+
+ device->state_count = DAVINCI_CPUIDLE_MAX_STATES;
+
+ ret = cpuidle_register_device(device);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to register device\n");
+ goto device_register_fail;
+ }
+
+ return 0;
+
+device_register_fail:
+ cpuidle_unregister_driver(&davinci_idle_driver);
+driver_register_fail:
+ iounmap(ddr2_reg_base);
+ioremap_fail:
+ release_mem_region(ddr2_regs->start, len);
+ return ret;
+}
+
+static struct platform_driver davinci_cpuidle_driver = {
+ .driver = {
+ .name = "cpuidle-davinci",
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init davinci_cpuidle_init(void)
+{
+ return platform_driver_probe(&davinci_cpuidle_driver,
+ davinci_cpuidle_probe);
+}
+device_initcall(davinci_cpuidle_init);
+